2 week 12 Flashcards
functions of blood? (5)
- transports gases, nutrients, hormones, metabolic wastes.
- regulates composition of interstitial fluid.
- restricts fluid loss at injury sites via blood clotting.
- defends against toxins and pathogens.
- regulates body temp by absorbing and redistributing heat.
what are the constituents of blood?
- plasma: 55%
- erythrocytes: 45%
- buffy coat (WBC + platelets): less than 1%
what is plasma made of?
- 92% water
- ions, organic molecules, trace elements, gases
- organic molecules = proteins like albumins (60%), globulins (36%), fibrinogen (4%)
where are most plasma proteins made? and does plasma have a greater or lesser concentration of proteins than interstitial fluid?
- liver
- greater
where do blood cells and platelets come from? what is this process called?
- stem cells
- hematopoiesis
main function of erythrocytes? how do they obtain their energy?
- transport oxygen and contain carbonic anhydrase needed for transport of carbon dioxide.
- no nucleus or organelles… obtain energy via glycolysis
describe the structure of a hemoglobin molecule
- identical alpha and beta subunits
- 4 heme groups (meaning it can bind 4 oxygens)
- iron in centre of heme group; non-covalent
what is hematocrit? average for males vs females?
- ratio of erythrocytes : total blood volume (centrifuged sample)
- males: 40-54
- females: 37-47
what is polycythemia? why can this be dangerous?
- adaptive response; higher hematocrit in low-oxygen environments.
- i.e., ppl living at high altitudes can have 60 hematocrit.
- dangerous because makes blood have high viscosity = clots.
describe the life cycle of erythrocytes (6)
- formation = erythropoiesis (in red bone marrow)
- stimulated by erythropoietin (released from kidney in response to low oxygen)
- no cell division of mature RBCs
- short life span = 120 days
- replace 2–3 million RBCs/second
- old RBCs filtered by spleen (and liver)
which portion of the RBC is eliminated? where does it go?
- heme!
- converted to bilirubin and excreted
what is…
a) aplastic anemia
b) nutritional anemia
c) pernicious anemia
d) renal anemia
a) drugs destroy stem cells
b) inadequate iron, folic acid, vitamin b12
c) deficiency in intrinsic factor like GI tract
d) kidney failure = low erythropoietin
what causes anemia? (5)
- genetics
- parasitic infections
- drugs
- autoimmune reactions (hemolytic)
- excessive blood loss (hemorrhagic)
what are the 4 blood types we discussed and what are the differences among them?
- A: has A antigens and antiB antibodies [42%]
- B: has B antigens and antiA antibodies [9%]
- AB: has A and B antigens; no antibodies (universal recipient!) [3%]
- O: has no antigens and antiA and antiB antibodies (universal donor!) [46%]
what is the main function of WBC? what is its structure like? (3)
- immune system
- nucleated
- several types
types of WBC and their functions? (5)
- neutrophils: phagocytes that circulate in blood for 7-10hrs and numbers increase during infections [50-80%].
- lymphocytes: B become plasma cells that produce antibodies, T activate immune cells and kill abnormal cells, and so do natural killers [20-40%].
- monocytes: migrate to tissues and become macrophages which phagocytose bacteria, present antigens to T cells and secrete cytokines [2-8%].
- eosinophils: defend against parasites via toxic granules [1-4%].
- basophils: defend against larger parasites and release histamine and heparin [<1%].
what is hemostasis? its 3 phases?
- stopping bleeding from a broken vessel.
- phases = 1) vascular spasm, 2) platelet plug formation, 3) clotting/coagulation.
describe the 3 phases in more depth
1) vascular spasm: injury = vasoconstriction thx to sympa system… reduces blood flow but does not stop bleeding.
2) platelet plug formation: von Willebrand factor (vWf) is secreted by platelets/endothelial cells + binds to collagen to activate platelets which form around site of vessel damage. platelets also release TXA2 and ADP!
3) clotting/coagulation: clot forms within plug to support it. does so by converting fibrinogen to fibrin (see common pathway slide).
where do platelets come from?
- break off into fragments from multinucleated megakaryocyte
- thrombopoietin produces megakaryocytes
- platelets themselves are anucleated but DO contain organelles
what do undamaged cells do to inhibit platelet aggregation?
endothelial cells release prostacyclin
describe the common pathway
- inactive 10 cleaved to 10a
- 10a, 5, calcium ions, and PF3 cleave inactive prothrombin into active thrombin
- thrombin cleaves fibrinogen to form fibrin mesh network (cleaved by 13a, to get stable mesh network)
describe extrinsic pathway
inactive 3 + inactive 7 + calcium form “active7 complex” that cleaves inactive 10 into 10a
describe intrinsic pathway
- inactive12 + collagen = active12
- active 12 cleaves inactive11 = active11
- active11 works with calcium to cleave inactive9 = active9
- active 9 works with 8 + calcium + PF3 to cleave inactive10 = active10!
what dissolves the clot when its no longer needed?
plasmin (activated by TPA)
thrombus vs embolus?
- thrombus: attaches to vessel wall
- embolus: free floating clot
what are hemophilia A and B?
- delay in formation of fibrin
- A = defective factor 8
- B = defective factor 9
what is thrombocytopenia? what do thrombocytopenia, vitamin K deficiency, and vWf disease have in common?
- thrombocytopenia = low platelet count
- all 3 = interference with platelet adhesion to collagen
treatment for vWf disease?
desmopressin to increase vWf levels
preventions/treatments for excessive clotting? (3)
- heparin: prevents thrombin activity
- warfarin/coumadin: prevents clotting (by suppressing vitamin K)
- aspirin: prevents TXA2 synthesis (prevents plug formation)
